Enable size_t to int truncation warnings in PPAPI

ppapi/proxy/file_ref_resource.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ppapi/proxy/file_ref_resource.h"
 
+#include "base/numerics/safe_conversions.h"
 #include "ppapi/c/pp_directory_entry.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/shared_impl/array_writer.h"
 #include "ppapi/shared_impl/file_ref_util.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/shared_impl/resource_tracker.h"
 #include "ppapi/shared_impl/var.h"
 #include "ppapi/thunk/enter.h"
 #include "ppapi/thunk/ppb_file_system_api.h"
 
 namespace ppapi {
 namespace proxy {
 
 FileRefResource::FileRefResource(
     Connection connection,
     PP_Instance instance,
     const FileRefCreateInfo& create_info)
     : PluginResource(connection, instance),
       create_info_(create_info),
       file_system_resource_(create_info.file_system_plugin_resource) {
   if (uses_internal_paths()) {
     // If path ends with a slash, then normalize it away unless path is
     // the root path.
-    int path_size = create_info_.internal_path.size();
+    int path_size = base::checked_cast<int>(create_info_.internal_path.size());
     if (path_size > 1 && create_info_.internal_path.at(path_size - 1) == '/')
       create_info_.internal_path.erase(path_size - 1, 1);
 
     path_var_ = new StringVar(create_info_.internal_path);
     create_info_.display_name = GetNameForInternalFilePath(
         create_info_.internal_path);
   } else {
     DCHECK(!create_info_.display_name.empty());
   }
   name_var_ = new StringVar(create_info_.display_name);
@@ skipping 215 matching lines @@
   callback->Run(params.result());
 }
 
 bool FileRefResource::uses_internal_paths() const {
   return (create_info_.file_system_type != PP_FILESYSTEMTYPE_EXTERNAL) ||
          !create_info_.internal_path.empty();
 }
 
 }  // namespace proxy
 }  // namespace ppapi